rx7tt95

So I'm over at N-Tech ready to slap on a brand new GT40 in place of a blown GReddy T78 (leaking oil). Get the old turbo off and notice that the supposed T4 inlet on the turbine housing is not a T4. It has an ever so slightly wider bolt spacing. Then we notice that due to the long turbine discharge which ends in a 4" vband, that it will not fit with the GReddy manifold as the vband hits the LIM. Things are not looking good at this point. Tomorrow we're having the discharge/vband cut off and a 3" vband welded on which will solve the clearance issues. The bolt holes will need to be elongated to line up as well. Definitely not a drop-in affair and a good reason just to buy an entire A-spec kit :-) It looks like the XS manifold (N-Tech had one around) would work a bit better. Definitely won't work with the GReddy stuff if you utilize the integrated V-band discharge on the GT40's turbine housing.

I'll have pics up comparing the two GT40 compressors (88 vs 82mm) and the GT turbine vs the Mitsubishi some time tomorrow. The turbines are quite different.

allrotor93

iTrader: (126)

so the gt40 isnt really a t4? i knew the greddy was different.

jdhuegel1

Wait... We JUST put a GT40 on a supra in plac of a Greddy T78 and it was a direct bolt on... Hmmmmm..

Carl Byck

Was that on a MKIV? Tell ME MORE???????????????????? I have a MKIV, and I was playing with that idea. As it sits I will be installing a Garrett 67mm with a 68 P trim on the Supra, and a GTQ 67 on my RX7 (basicle a Q trim TO4R)

jdhuegel1

It was on a 95. Don't have the specs right in front of me, but I know the hotside A/R was 1.38. Quite laggy, but 4000 RPM is out of this world...

Carl Byck

Full boost by 4000 is really not bad on a MKIV. A 1.38 hotside however is way too big, a .81, maybe a .96 would be about right. A GT40 is very close in size to a TO4R, and those are the two sizes generally used. The .96 is the standard AR on the HKS TO4R kit, but is considered a slow spool. Anything below 3800rpm would be cosidered very good spool. Many of the large frame turbos do not spool til 4500 rpm or later. What RWHP did you see? I would imagine mid 600s, although properly set-up that turbo could make low 700s. Carl

rx7tt95

It's finally installed thanks to the hard work of Nick Riefner and N-Tech. I essentially brought a turbo to him and he made it work with MUCH effort. I will have a full report later as I did not get any sleep last night. I'm not hitting the gas too hard yet as the turbo should be broken in a bit before letting her rip. I need to adjust my boost controller as I hit 1.3 bar in a heartbeat. This thing spools but I don't think it'll have the top end punch of my last turbo (and more on that one later too).

The GReddy gasket did not line up with the Garret's flange. The GReddy gasket DID line up with the XS Engineering manifold. It's a long story, but I came across a T4 style gasket that was made for the Garrett GT37 in Europe (Italy to be exact) and it even had a different bolt pattern.

The standard Garrett housing on the GT40 is .94 with the 82mm wheel and 1.35 on the 88. There's nothing smaller unless you go custom (precision is working on custom hot side housings apparently but they're not ready yet). You cannot get the 88mm wheel with the .94 housing says one Garrett dealer. Says the pressure ratio f/r would be all wrong. The 88mm compressor wheel uses a different turbine trim but the same diameter.

jdhuegel1

Carl,

Not sure what it made.. I'm pretty sure it was around 600.. Sure seemed like it!! The car is having a 100 shot of Nitrous installed as well.. I guess to compensate for the lag (I didn't even see it!) It's a fully build motor, so with a good tune he should see some rediculous numbers. Nice looking car too!

I just can't wait to see my T04R perform..

Oh, sorry to hijack the thread!

Carl Byck

rx7tt95, that turbo s/b good for ~500-530 @ 25 psi. is that where you are headed? Judge, I'll have mine(TO4R .81 GTQ wheel) in two weeks

bladz311

iTrader: (1)

Congrats on the install!!!! I wonder what the spool is like on the 88, hmm.

rx7tt95

I have a feeling the 88mm wouldn't be much worse spool wise...wondering if I could just upgrade my compressor and stay with the .94 hot side and the different turbine trim. Too much work to modify that turbine housing! WAAAAY too much. Nick would kill me if I decided to swap it out. We literally worked all night getting it set up and in the car. PITA.

I'd be happy with those numbers Carl. I'd like to at least have 425 to the wheels on pump at 17psi. It's raining pretty hard down here today so not too much to report. Need a longer silicone coupler too as I have a short one that's blowing off. I expect this thing to spool about as well as the twins sequentialy (really). Noticed the car is a bit louder with this turbo (fewer turbine blades, less restriction?) and my gas mileage off boost has improved. The full-on GT40R ball bearing setup has got to be killer. Talking with a Garrett rep (who also reps for IHI and Mitsubishi), he feels the GT stuff is the hottest thing on the market and that Garrett is really pushing the envelope with agressive wheels. There is apparently NOTHING out there comparable.

evot23

iTrader: (17)

ahhhh rx7tt95...you make me wanna go single. no where to those crazy numbers though. Good to hear Nick and N-tech still going strong to help out even with the Z's in place.

bladz311

iTrader: (1)

I've been waiting for my new credit card to come in the mail so I can get the gt40r bb kit. Where the hell is my credit card?! haha. I finished installing the nitrous foggers today . I can't wait until its done.

boostedyellow7

so do you like this thing better than the t78?

rx7tt95

I haven't had much time to tune yet (next month when I am off on two weekdays) but as of right now, I do like it more than a T78. The car is sooo much more driveable and the midrange hit is amazing. Truth be told, I haven't redlined her in third yet, just first and second. Having trouble keeping the boost down. I am still very rich with my EGT's peaking at about 840 celcius. I saw 1050C max with the old turbo. I'm probably pretty rich up top (and it feels it) so I'll need to hit the dyno to lean out the top end and get boost under control. There's way too much traffic down here this time of year to do anything on the street with datalogging and the wideband.

boostedyellow7

cool thanks for the info. im starting to lean towards this kit from the t 78 to this

rx7tt95

After really examining the T78 kit with Nick from N-Tech, it's NOT a well designed kit in terms of placement. Due to the manifold design and turbine placement, many items are exposed directly to substantial heat including the oil drain line. If you have a T78 GReddy kit and don't wrap/insulate that line, you're asking for trouble. One would be much better off with the A-spec kit (all Vband) or say the XS Engineering manifold.

hyperion

iTrader: (2)

...I'm really, really not trying to start a flame war here, so I'll just ask if you mean:

1) at 4000 RPM, the the GT40 will build boost as quickly as the twins, or

2) the GT40 will make near-full boost at 2500 RPM from a slow, rolling start in 3rd gear

Thanks,

-ch

rx7tt95

It'll make almost full boost for twins (10psi) at 3200rpm (and 16-18psi by 3800rpm)starting from a roll in third. I have an undivided manifold. Go fully divided and I would expect to see boost a few hundred rpm sooner. I'm actually having trouble controlling boost in third and fourth. I can actually floor this thing at 1500 rpm and see 3kg of boost almost immediately. Yesterday I floored it in 5th (remember what the twins felt like in 5th?) and spiked to almost 1.4kg at 3800 to 4000 rpm when I wasn't looking.

Now take into account that the GT40 is flowing more CFM (ported engine) AND has cooler discharge temps. I am also untuned and undoubtedly very rich in the lower rpm/high boost ranges. I am also using the smaller 82mm compressor, not the 88 and a .94 hot side, T4 sized.

Unfortunately, work is just killing me (as is the traffic!) but I hope to have a few logs up soon on the Datalogit list as soon as I can figure out why I am getting boost spikes. Just too busy at the moment to do any real significant testing.

Nick (N-Tech) just sent me a bunch images I took with his camera during the installation. I have comparisons between the Mitsu turbine and the GT series turbine and a few other interesting goodies. I'll try and post them later tonight with a better writeup and take a few boost response notes today in between lights/traffic

vspecpgt

wow.... i really wanna get the aspec kit now michel....

btw... god traffic does suck.... fort myers was horrible!!!!

rx7tt95

Isnt that the truth...US 41 was backed up from Ft. Myers all the way into Naples yesterday. I literally cant get out of second gear right now. As I said earlier, the complete kit w/ball bearing is really the way to go. It is just too much trouble trying to get this turbo to work with an existing kit as Nick and I can attest to. But the new GT stuff is so nice I feel it is worth the effort to swap out kits and go with a GT series turbo. I will have a big post later tonight which goes into detail about the entire installation process and my thoughts on the GT series (and a few notes from a few turbo distributors). Nick got all the pics to me earlier today. It is really quite interesting the way Garrett has gone compared to other turbo companies.